The invention relates to an axial piston engine with a filling pump integrated in a receiving bore of the axial piston engine and the features according to Claim 1.
To compensate for internal leakage losses and the oil quantities deliberately taken out for cooling and for filtering, closed-circuit hydraulic pumps require what is known as a filling pump, which is as a rule attached to the end housing or integrated into it as an auxiliary pump.
Various types of pump can be used as a filling pump. Internal gear pumps, for example, which offer the advantage that the main shaft of the axial piston engine can be guided through the filling pump even in the case of a great shaft diameter, the main shaft at the same time driving the filling pump as well, are suitable. The drive of the filling pump can also be designed in such a way that the filling pump has its own shaft with separate bearing, which is in turn driven by the main shaft.
All constructions have essentially two problems to contend with: on the one hand, the unavoidable operating forces acting on the shaft lead to the latter being shifted out of its optimum position, elastic deformations of the shaft moreover arising, owing to which constraining forces are in each case exerted on the filling pump. These constraining forces caused by shaft shifts and shaft deformations have to be kept away from the filling pump to the greatest extent possible as otherwise they also load its parts radially and axially, displace them and possibly even misalign them, which results in increased wear and can lead to failure of the filling pump. On the other hand, the lateral play of the filling pump and also the evenness, surface structure and machining or coating of the walls axially delimiting the filling pump have a great influence on its volumetric efficiency and its reliable functioning. This results in manufacturing being highly complex and especially difficult to effect in practice when these walls are to be fashioned in the pump housing itself.
Conventionally, the filling pump is therefore in many cases built into a separate, unilaterally open housing in pot form with a very accurately executed bore depth for the lateral play tolerance. This housing together with the filling pump is then inserted into the end housing as a subassembly. The construction requires a great deal of construction space and is expensive. The construction space requirement is due to inter alia the necessary rigidity of the filling pump housing against deformation caused by the operating pressures and the forces exerted by the necessary fastening bolts. Above all, involved sealing of the entire construction is necessary as well.
By means of the invention, an axial piston engine with a compact filling pump which requires low component rigidity is to be produced.
This object is achieved with an axial piston engine according to Claim 1.